KINSHASA, Democratic Republic of Congo — The opposition presidential candidate who says he was cheated from victory in this vast country’s long-delayed election said Friday that he would petition the Constitutional Court for a recount.

The announcement by the candidate, Martin Fayulu, who had been shown by polls to be heavily favored in the race, came as questions about the fairness of the vote intensified. The United Nations Security Council held a meeting to air concerns with Congolese officials, including the leader of the country’s Electoral Commission.

The Dec. 30 election had raised hopes for the first peaceful and democratic transfer of power in the Democratic Republic of Congo since independence in 1960.

The election had been repeatedly delayed by the country’s longtime leader, President Joseph Kabila, who came to symbolize the reluctance of some entrenched African leaders to relinquish authority.

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Felix Tshisekedi, a largely untested candidate, received more than seven million votes, according to results released by the Electoral Commission.CreditCaroline Thirion/Agence France-Presse — Getty Images

The provisional results released early Thursday by the Electoral Commission showed that a largely untested opposition candidate, Felix Tshisekedi, who had been given little chance of a victory, received more than seven million votes, compared with more than six million for Mr. Fayulu. The candidate backed by Mr. Kabila trailed the others, drawing more than four million votes.

The tallies immediately raised suspicions that Mr. Kabila, knowing his candidate could not possibly win, had cut a deal with Mr. Tshisekedi to share power and prevent Mr. Fayulu from claiming victory.

Those suspicions were reinforced by a bishops conference of the Roman Catholic Church, which had deployed 40,000 observers around the country for the vote and has suggested that its polling data show Mr. Fayulu was the runaway winner.

Mr. Fayulu said that he would go to the Constitutional Court on Saturday to demand a recount. “When you know you are in the right, you are not allowed to remain home,” he told supporters in Kinshasa, the capital.

According to Congo’s electoral law, the Constitutional Court must validate the Electoral Commission’s provisional results, but candidates also have the right to contest them.

The disputed outcome has raised fears of violence in the nation of 80 million, but Kinshasa and other major cities have so far been relatively calm.

António Guterres, the secretary general of the United Nations, which has maintained a heavy peacekeeping presence in the country for years, has exhorted “all stakeholders to refrain from violence and to channel any eventual electoral disputes through the established institutional mechanisms.”

At the Security Council on Friday, Western diplomats emphasized that they wanted to see transparency in the Congolese voting tabulations. Karen Pierce, the British ambassador, noting the wide disparity between the official results and the tally by the Catholic bishops conference, said the “data and methodology of voting must be examined.”

Speaking by a videoconference link to the council, Corneille Nangaa, the leader of the Electoral Commission, insisted that the vote had been carried out “in conformity with the legal framework of elections in our country.”

Mr. Nangaa suggested that the only choice was to accept the results or call a new election. He discouraged the idea of an annulled vote even as he acknowledged the election had been far from flawless.

“There were myriad obstacles in these elections — you cannot clean your house overnight,” he said. “We saw the election in the United States and the complaints there. Elections are never perfect.”

Kimiko de Freytas-Tamura reported from Kinshasa, and Rick Gladstone from New York.

A version of this article appears in print on , on Page A7 of the New York edition with the headline: Fraud Claim In Congo Vote Leads to Call For Recount. Order Reprints | Today’s Paper | Subscribe